Potterton Boilers Error Codes

E01

Boiler will not ignite, display shows E01, no flame symbol, heating and hot water not working

Ignition Lockout / Flame Failure

E02

Boiler locks out shortly after starting, display shows E02, burner shuts down within seconds

Flame Detection Failure / Flame Signal Lost

E03

Boiler attempts to start then shuts down with E03, fan may run briefly, no ignition

Fan / Air Pressure Switch Fault

E04

Boiler shows E04 and will not fire, may occur intermittently during operation

Flow Thermistor / NTC Sensor Fault

E05

Boiler displays E05, shuts down on high temperature, may be hot to touch on flow pipe

Overheat Thermostat Trip / High Limit Lockout

E06

Boiler shows E06, hot water temperature unstable or boiler shuts down during hot water demand

DHW Thermistor / NTC Sensor Fault

E09

Boiler displays E09 and will not operate, often after power surge or water ingress

PCB / Control Board Fault

E10

Boiler shows E10, system pressure gauge low, boiler will not fire

Low Water Pressure / System Pressure Fault

E11

Boiler intermittently locks out with E11, especially when heating is on for long periods

Return Thermistor / NTC Sensor Fault

E119

Boiler shows E119, pressure gauge near zero, boiler will not fire

Low System Pressure Lockout

E12

Boiler shows E12, may be accompanied by noisy operation or rapid cycling

Flow/Return Temperature Differential Fault

E13

Boiler displays E13 and shuts down, often associated with flue or condensate issues

Flue Gas / Combustion Safety Fault

E133

Boiler displays E133, no ignition, often after gas supply interruption

Ignition Lockout / Gas Supply Interruption

E15

Boiler shows E15, no heating or hot water, fan may not start

Fan Speed / Fan Feedback Fault

E16

Boiler intermittently locks out with E16, particularly during hot water use

DHW Flow Sensor / Turbine Fault

E160

Boiler shows E160, fan-related error, boiler will not fire

Fan Fault / No Fan Feedback

E168

Boiler intermittently shows E168, random lockouts, often after power fluctuations

General PCB / Power Supply Fault

E193

Boiler shows E193, often associated with pump or flow issues on system boilers

Pump / Flow Detection Fault

E20

Boiler shows E20 and will not start, often after wiring changes or thermostat replacement

External Control / Thermostat Fault

E20X

Boiler shows a generic E2x series code related to sensor or temperature faults

General Temperature Sensor / NTC Fault

E25

Boiler displays E25, noisy boiling or kettling sounds from the heat exchanger

Primary Heat Exchanger Overheat / Flow Restriction

E28

Boiler shows E28, often associated with condensate issues or blocked trap

Condensate Drain / Trap Fault

E40

Boiler displays E40, no response to control inputs, may be after power cut

Communication / Internal Bus Fault

E50

Boiler shows E50, fan runs but no ignition, may indicate gas valve or combustion fault

Gas Valve / Combustion Control Fault

E60

Boiler displays E60, hot water priority or diverter valve related issues, heating may not work

Diverter Valve Position Fault

Symptom

Boiler cycles on and off frequently, radiators never reach full temperature

Short Cycling / Control Strategy Issue

Symptom

Boiler emits a burning smell or visible smoke from casing

Overheating / Electrical Burn

Symptom

Boiler flue terminal dripping water or staining the wall outside

Condensate / Flue Drainage Issue

Symptom

Boiler frequently loses pressure and needs topping up every few days

Chronic Pressure Loss

Symptom

Boiler leaking water from underneath the casing or from pipe connections

Internal Water Leak

Symptom

Boiler locked out with red light but no code on older Potterton models

Generic Lockout (Legacy Boiler)

Symptom

Boiler makes loud banging or knocking noises when starting or stopping (water hammer / kettling)

Hydraulic Shock / Kettling

Symptom

Boiler pressure rises rapidly when heating is on and discharges water outside

Over-Pressurisation / Expansion Vessel Failure

Symptom

Boiler runs but makes a high-pitched whine or humming noise

Fan or Pump Acoustic Noise

Symptom

Boiler runs but radiators do not get hot or only partially warm

Poor Circulation / System Balancing Fault

Symptom

Boiler will not start at all, no lights or display

No Power / Electrical Supply Fault

Symptom

Hot water temperature fluctuates or runs hot then cold during shower use

Unstable DHW Temperature Control

Symptom

No hot water from taps but central heating works normally (combi boiler)

DHW Priority / Diverter Valve Fault

Symptom

Radiators get hot when only hot water is demanded (combi or system with 3-port valve)

Cross-Flow / Motorised Valve Fault